Mode monitoring and identification through distributed radio

ABSTRACT

Independent radio communication devices can share network information directly with each other in the local area using an independent wireless link. This network information encompasses synchronisation information, interference, network configuration, neighbour cell list, paging requests, etc., and can be relevant to multiple networks, frequency carriers and/or air interface modes. Sharing the information reduces the processing requirement, the power consumption, and the bandwidth consumption of devices.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The preset invention relates to a method of sharing resourcesbetween devices using wireless connectivity, and in particular to thesharing of a radio link to a remote base station or access point betweenseveral devices located within a small geographical area.

[0003] 2. Description of the Related Art

[0004] A mobile phone network comprises a series of base stationscovering a range of geographical areas, and a multiple of handsets. Eachhandset communicates with one of the base stations, and the particularbase station used is selected depending on factors such as geographicallocation, interference, channel loading, etc.

[0005] However, an increasing problem with this arrangement is that thenumber of people using mobile phones is increasing rapidly, and there isonly a limited amount of bandwidth available for transmission of signalsto and from individual handsets. Radio links from laptop computers,personal organisers, etc., are also becoming much more common, forexample, to connect to the internet (e.g. WAP), for fax, videoconferencing, telematics, or for remote control of hardware devices suchas domestic appliances in the home.

[0006] The traditional approach to this problem of limited bandwidth hasbeen to introduce more and more complex methods of scheduling. Airinterface modes such as TDMA (time-division multiple access), e.g. GSM(Global System for Mobile communications, are based on dividing timeinto slots and placing the signals of different users into differenttime slots. Another way of using the available bandwidth, which may bemore efficient, is CDMA (code division multiple access), in whichsignals from multiple users are sent at the same time in the samefrequency band, with the spectrum of each user's signal spread throughthe bandwidth of the frequency band according to a code sequence uniqueto the user. One of the most important implementation of CDMA is W-CDMA(wideband CDMA), which uses a 5 Mhz carrier, allowing the possibility ofmultimedia transmission such as video streams.

[0007] In the earlier implementation of CDMA, blind interfrequencyhandover could result in inadequate call quality. Instead, a mobileradio had to be able to monitor the signal strength and and quality ofanother carrier frequency while still maintaining the connection in thecurrent carrier frequency. In the case of W-CDMA, this need can beovercome by having the system enter compressed mode to simultaneouslymonitor other carriers. In compressed mode, the system is manipulated toprovide a number of contiguous slots free for measuring other channels.However, compressed mode requires a highly complex level of networkmanagement. A variety of methods can be used to establish compressedmode, for example through reduced spreading factor (perhaps withincreased transmit power), increased puncturing, or higher layersignalling. In each case, the mobile terminal will suffer as the rawthroughput of the channel is being reduced. In the case of reducedspreading factor, the receiver may experience greater interference (andcreate greater interference, if a higher base station transmit power isused). With puncturing, the error detection/correction properties of anycoding may be impaired. Finally, with higher layer signalling, certainsegments of data must be scheduled to not be transmitted which maydegrade overall perceived quality.

[0008] In general, a mobile device may have to spend a significantamount of time monitoring: other carriers, base stations; access pointswithin the same radio mode; or carriers, base stations or access pointswhich are attached to another mode. This monitoring time may impact onthe throughput (as observed by the user), power consumption, and thelatency which is introduced before a handover to an alternative carrier,base station, access point, or mode.

[0009] In addition to the user of more complex air interface modes,wireless devices themselves are becoming increasingly complex, as alarger and larger set of radio functionality and applications arerequired. The trend has been towards integrating all the requiredtechnology in a single device, to allow the user flexibility ofoperation. This desire of highly complex functionality, flexibility andmultiple air interface modes leads towards the “Software Defined Radio”concept where a flexible architecture is employed to fulfil allrequirements.

[0010] In recent times it has also become feasible to provide anindependent low power interconnection between devices through the use ofa Wireless Personal Area Network (WPAN), such as a Bluetooth enabledWPAN. Within WPAN equipped devices, this mode of operation is likely toexist in addition to (and independently of) other capabilities, such as:cellular or Wireless Local Area Network (WLAN) transceivers; significantprocessing power; and other features. The provision of this independentlink gives the potential for a device to utilise the resources of otherdevices that are attached with the wireless interconnection. Thisconcept of a virtual device that is formed from a number of separatewireless units is described here as a distributed wireless system ofdistributed radio.

[0011] The separate wireless units are likely to be manufacturedindependently and even independently owned, but are linked through apreferably common short-range wireless link with a common communicationsprotocol. It would also be possible to use more than one type of linkwithin the WPAN, although there may then be more problems with the upperlayers in terms of forwarding information over multiple link types.

[0012] A further problem with mobile radio device is that they tend tobe battery operated, but the radio links to the base station must be ofreasonably high power. This is a major factor in draining the batteries,and reducing the amount of time before recharging is necessary.

BRIEF SUMMARY OF THE INVENTION

[0013] According to the present invention there is provided acommunication device comprising: first communication means forcommunicating with a base station or access point over a first network;and second communication means for communicating with one or more othercommunication devices over a second network, said other communicationdevices being able to communicate over said first network, wherein saidcommunication device is adapted to send and/or receive networkinformation of the first network over said second network.

[0014] The present invention uses the concept of distributed radio toreduce the problems of the limited available bandwidth on the radionetwork, the large amounts of processing required for scheduling andmonitoring, and the battery drain resulting from high power radiotransmissions. Resources are shared between devices using local lowpower wireless connectivity. Preferably, the distributed radio conceptis utilised to support efficient monitoring of network information onone or more radio networks.

[0015] It is through exploiting the local wireless link that the novelaspects of this invention are achieved. Networking information availableon a device is exploited by another device. It should be noted that thedistributed radio concept applies equally to a large number ofinterconnected devices or to a limited number.

[0016] With the present invention, the network information (networkmonitoring information) that is available to one radio communicationdevice is shared with other radio device(s) within a small geographicalarea. Provided this area is reasonably small and homogeneous, thenetwork monitoring information will be valid across the entiredistributed radio. Shared network information can includesynchronisation information, interference, quality of service, networkconfiguration, neighbour cell list, paging requests, etc. and can berelevant to multiple networks, frequency carriers and/or air interfacemodes.

[0017] Sharing of available network information can reduce the batteryconsumption of the devices and time taken to perform monitoring withinthe distributed radio. Furthermore, it may reduce the requirements fornetwork management. For example, in the case of W-CDMA, monitoringthrough a distributed radio may remove the need to enter compressedmode.

[0018] The WPAN could include any mechanism for providing a wirelesslink between devices, such as the use of Short Range Devices (SRDs),Infrared connections, and industry standards such as Bluetooth. The WPANsystem is preferably able to operate concurrently with the radiocommunication system within all devices.

[0019] Depending on the exact WPAN used, different types of WPAN networkconfigurations may be used. For example, a network in which each devicecan communicate directly with every other device, or a network in whichinformation can be forwarded between those devices which do not havedirect links. The exact topology is more likely to be influenced by theformat of the WPAN short range link itself. For example, Bluetooth usesa master-slave arrangement, and it would be reasonable for the Bluetoothmaster to act as the radio network monitoring device, and be able toforward on information such as paging requests. Alternatively, it ispossible to configure a slave to be the monitoring device, in which casethe monitoring information is forwarded to the master, and thenforwarded on by the master to other slaves. A WPAN network topology inwhich devices forward information which is not intended for them couldprovide enhanced coverage within a certain area. However, it would beimportant to ensure the quality of the measurement for all devices. Theforwarding devices may not themselves be interested in the measurementreports (or indeed be equipped with that radio mode).

[0020] The bandwidth of the WPAN link could either be small, onlyallowing the relaying of essential control signals, or it could be muchlarger, allowing full data relaying. A distributed radio according tothe present invention could then also provide backup means for anyindividual radio device within it, switching to another radiotransmitter in the case of the radio link to that device breaking down,e.g. due to transmitter failure, low battery, localised interference,etc.

[0021] The system may associate some form of reliability indicator withthe network monitoring information. This could take the form of ameasure of similarity of the radio environment as seen by the clientdevice (receiving information from the monitoring device) and monitoringdevices (which monitor the network to provide information to theclients), such as the path loss between the devices. This would give anindication of the homogeneity of the radio environment which encompassesthe distributed radio. Alternatively, the client device could obtainnetwork information from the monitoring device whilst the client deviceitself is still monitoring. By comparing the two sets of information,the reliability of the monitoring devices measurement reports will beestablished. Once the veracity of the information is established, theclient device can then leave the required functionality to themonitoring device. The client device may periodically enter monitoringmode to check the reliability of the monitoring device's reports.

[0022] Devices may indicate their relative (or absolute) positions toeach other and/or the serving network, in order to establish thevalidity of network information derived from another device within thedistributed radio. Network information may be time-stamped to indicatewhen the measurement was taken. This allows the validity of theinformation to be established.

[0023] A device may enter low power mode, in which the radio network isnot being monitored by that device. Instead, a designated monitoringdevice will forward any paging requests to the desired device via theWPAN link.

[0024] The radio network monitoring device may initiate response to theradio network on behalf of the client device. This could occur inresponse to a paging message. The monitoring device would respond to theradio network with the appropriate message, allowing the client devicemore time to obtain resynchronisation.

[0025] In the case where two devices in the WPAN are connected todifferent radio networks, and the first device wishes to switch over tothe network of the second device, the second device initiates aconnection or handover request to its radio network on behalf of thefirst device. If the second device sets up the connection for the firstdevice in this way, it can then relay information to the first device toconfirm that sufficient capacity is available. When handing over betweenmodes, using handover in this way removes the need for a device toretune and start the other mode to check network loading, availability,etc.

[0026] The actual choice of which device is picked to be the monitor maybe dependent on a number of factors. For example, on whether the devicehas mains power, and if not, then on the remaining battery power; onwhether the device is already connected and active; on which device hasthe most similar radio link to all other devices (which may imply in thegeographic centre of the distributed radio); on radio performance (themonitoring device should have an equal or better sensitivity as comparedto other devices); or on user preference. Where the decision is made isa complex question, and partly will depend on the topology of theunderlying WPAN. A centralised, master controlled network may use themaster to determine which device should be the monitor (which may or maynot be itself). However, a centralised architecture could still use someform of distributed decision making regarding which device should be themaster. Similarly, a decentralised topology may adopt a centralised ordecentralised structure for choosing the monitor. In general, it seemsthat a centralised choice of the monitoring device would be easier toimplement, as one device can collate capabilities before making thechoice.

[0027] Devices within the distributed radio may exchange informationabout multiple networks, frequency carriers and/or air interface modes.This information encompasses synchronisation information, loading level,network configuration, neighbour cell list, etc. These factors can beused to determine whether to handover to another network, frequencycarrier and/or air interface mode.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Preferred embodiments of the present invention are now described,with reference to the accompanying drawings, in which:

[0029]FIG. 1 shows a first embodiment of the invention, in which thedevices within the distributed radio are all connected in the same mode;

[0030]FIG. 2 shows a flow chart summarising the steps taken by thedistributed radio in the first embodiment of the invention;

[0031]FIG. 3 shows a second embodiment of the invention, in which thedevices within the distributed radio are connected in different modes;and

[0032]FIG. 4 shows a flow chart summarising the steps taken by thedistributed radio in the second embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

[0033] Two embodiments of the present invention will now be described.In the first embodiment, the devices within the distributed radio areall connected in the same mode (e.g. all GSM). In the second embodiment,the devices are connected in different modes (e.g. some in GSM and somein W-CDMA).

[0034] In a first embodiment of the invention, illustrated in FIG. 1,all devices within the distributed radio are connected to a radionetwork in the same mode. One device monitors the network and sharesrelevant network information with other devices within the distributedwireless system. This information could include (but is not limited to)paging messages, synchronisation, neighbour cell (or access point)monitoring.

[0035] In this embodiment, sharing of network monitoring informationreduces power consumption for the devices that are not currently active.This may allow user devices to enter a low power mode, where nocommunication with the network occurs directly, and instead, networkinformation is routed via the low-power WPAN link.

[0036] This can also be exploited to reduce requirements on the network.For example, a terminal operating in W-CDMA in dedicated mode mayrequire the use of compressed mode to monitor other W-CDMA carriers(allowing the terminal to handover to them). This needs additionalcomputation within the terminal and requires the network to schedulecompressed mode operation. Here, this information can be obtained fromanother terminal connected within the distributed radio, reducing powerconsumption and network requirements.

[0037] In FIG. 1, three radio devices are shown, linked by a WPAN 108—avoice phone 100, a PDA 101, and a laptop computer 102. Each devicecomprises a WPAN module 103, a radio network module 104, and a radioantenna 105. The radio network module 104 includes means for connectionmanagement (CM), mobility management (MM) and radio resource management(RRM). Each device initiates registration on the radio network, eitherdirectly or by one device registering all other devices. Each deviceshould now be camped on, i.e. ready to make a call. The protocolmanagers 106 of the devices then make a collective decision about whatthe optimum monitoring configuration should be. In the example shown, itis decided that the laptop 102 should do all the monitoring. The laptop102 now listens for all paging messages for all devices within thedistributed radio. When the radio environment changes (e.g. more basestations become visible) or when updated cell information becomesavailable, this information is passed to the remaining devices via theWPAN link 108. When an incoming paging request is received for the phone100, details and timing information is passed to the phone 100 via theWPAN 108. The phone 100 accepts the paging request and using timinginformation from the laptop 102, synchronises to the network andinitiates random access and call set-up via its own modem in the radionetwork module 104. An alternative would be for the laptop 102 to issuethe random access request on behalf of the phone 100, whilst the phone100 is synchronising. The phone 100 now enters connected mode. Due tothe new configuration (the phone 100 is now connected), it may benecessary to update the designated monitoring device. If devices leave(or enter) the distributed radio, it may be necessary to reconfigure andreassign the role of monitoring device. Alternatively, if theenvironment changes (e.g. the monitoring device moves away from theother devices) it may be necessary to reconfigure.

[0038] The steps taken by the distributed radio in this first embodimentare summarised in the flow chart shown in FIG. 2.

[0039] A second embodiment of the invention is shown in FIG. 3, in whichdifferent air interface modes are used within the distributed wirelesssystem. In this case, information can be obtained through thedistributed radio to facilitate mode handover. Unlike the previousexample, it is more likely that the information exchange will be aone-off event (preceding inter-mode handover, for example) rather than acontinuous series of events. Again, the user does not need to derive theinformation of other modes directly (e.g. GSM monitoring duringcompressed mode in W-CDMA). Instead, devices within the distributedradio which are connected using different air interface modes shareinformation on the current serving base station, neighbour cell listsfor that mode/network, etc. It may be necessary for there to be somedegree of location awareness within the devices, as it can only beassumed that all devices within the distributed radio can connect to thesame mode/network if they are relatively close. This location awarenesscould be limited to a simple indication of range between monitoring andrecipient devices; if this range is below a certain threshold, then theinformation is assumed to be valid and can be applied. A very simplemeasure of range would assume that if all the devices are connected, andthe transmit power is sufficiently low, then the geographical extent ofthe WPAN network will be small. A more complex method is to use locationequipped devices (with e.g. GPS) and exchange this information as partof the information exchange. However, range will not necessarily givethe best view of homogeneity from the radio access point of view. Forexample, with two devices which are very close (and therefore have agood WPAN link), one may be obscured from the base station by a buildingcorner, while the other is not. Generally, a more reliable technique maybe the parallel measurement method, where the recipient device does asimilar measurement to the monitoring device, to ensure the validity ofthe link. It may be possible to determine the relative homogeneity ofthe WPAN network by a simple examination of a received signal strengthindicator (RSSI) coupled with knowledge of antenna gains and transmittedpower. It is desirable not only to measure the similarity of the radioenvironments, but also the similarity of their rates of change. Thiscould be extended to say that a variable time threshold could be set forretesting similarity. If, for example, the environments are similar andnot changing then the devices can share information for a long timebefore rechecking the environment. If the radio environment is rapidlychanging then the time period may have to be shortened.

[0040] In FIG. 3, two radio devices 113, 114 are illustrated. One ofthese is connected in GSM mode to a GSM base station 109 via a GSM link111, whilst the other is in W-CDMA mode connected to a W-CDMA basestation 110 via a W-CDMA link 112. The W-CDMA device 114 is a dual modeterminal, also capable of operation in GSM mode, and in the exampleshown is in a state when handover to GSM is desirable (e.g. poorcoverage for W-CDMA in this region). The relevant information regardingwhether to hand over to GSM, whether connection is permitted by theoperator, appropriate base stations, channel configuration, etc. isobtained directly from the GSM device 113. Since the GSM device 113 isalready connected in this mode, and to the relevant network, noadditional monitoring is required. The overheads required for thisoperation are the power consumed by the WPAN system to forward on therelevant network information.

[0041] In this second embodiment, the dual mode device 114 issues apaging request (and e.g. associated service discovery protocol) toestablish if any WPAN-equipped devices in the vicinity have networkinformation that it requires. Another device can then respond if it hasthe relevant information. This response may indicate details of theavailable information (network type and operator, etc.). The dual modedevice 114 selects one or more monitoring devices from those who haveresponded to the request (in this case from the GSM device 113), andelicits the required information. The particular device(s) chosen toprovide network information depends on a number of factors, for exampleon whether a relevant network type and operator is supported, and on therelative range. The selected monitoring devices forward the desiredinformation to the recipient device. Thus in FIG. 2, the GSM device 113provides GSM network information for the dual mode device 114. Thus theentire exchange of information on network capability and of networkinformation is performed via the WPAN link, and may occur simultaneouslywith established dedicated link(s) in the connected device(s).

[0042] The steps taken by the distributed radio in this secondembodiment are summarised in the flow chart shown in FIG. 4.

[0043] Thus, the present invention provides a system for reducing thebandwidth required for portable devices to communicate with a basestation over a radio network. In addition, by avoiding power hungrycommunications with a distant base station of a network, the batteryconsumption of portable radio devices can be considerably reduced. Theinvention also allows a reduction in the computational requirements of aportable radio device for scheduling and monitoring, in particular,potentially eliminating the need to use compressed mode W-CDMA. Thesystem additionally provides a method of error checking and/or errorcorrection by comparing the radio signals received on the same channelby more than one radio device as well as providing a method of checkingthe quality and uniformity of the radio environment by comparing theradio signals received on the same channel by more than one radiodevice.

What is claimed is:
 1. A communication device comprising: firstcommunication means for communicating with a base station or accesspoint over a first network; and second communication means forcommunicating with one or more other communication devices over a secondnetwork, said other communication devices being able to communicate oversaid first network, wherein said communication device is adapted to sendand/or receive network information of the first network over said secondnetwork.
 2. A communication device as claimed in claim 1, wherein saidfirst communication means can operate concurrently with said secondcommunication means.
 3. A communication device as claimed in claim 1 or2, wherein said second network operates using one of: Wireless PersonalArea Network; Short Range Device, infrared connections; or Bluetooth. 4.A communication device as claimed in any one of the preceding claims,wherein the network information includes network monitoring informationwhich has been derived from the first network of a particular device. 5.A communication device as claimed in any one of the preceding claims,wherein said network information includes information about a singlenetwork, frequency carrier and/or air interface mode.
 6. A communicationdevice as claimed in any one of claims 1 to 4, wherein said networkinformation includes information about multiple networks, frequencycarriers and/or air interface modes.
 7. A communication device asclaimed in claim 6, wherein said network information is used todetermine whether or not to hand over to another network, frequencyand/or mode.
 8. A communication device as claimed in any one of thepreceding claims, wherein said first communication means can enter amode in which communication over the first network is suspended.
 9. Acommunication device as claimed in any one of the preceding claims,wherein said network information includes information on alternativeW-CDMA carriers.
 10. A communication device as claimed in any one of thepreceding claims, wherein network information on the same channel isreceived from more than one other communication device and the resultsare compared to determine the reliability of some or all of the othercommunication devices.
 11. A communication device as claimed in any oneof the preceding claims, further adapted to receive a measure of thereception quality of the first network as seen by one or more of saidother communication devices and monitoring the similarity to determinean indication of the homogeneity of the environment which encompassesthe devices in the second network.
 12. A communication device as claimedin any one of the preceding claims, further adapted to send and/orreceive information of their relative or absolute positions relative toanother communication device and/or the serving network, in order todetermine the validity of network information derived from anothercommunication device within the second network.
 13. A communicationdevice as claimed in any one of the preceding claims, wherein saidnetwork information is time-stamped to indicate when the measurement wastaken.
 14. A communication device as claimed in any one of the precedingclaims, further adapted to initiate a response to the first network onbehalf of another communication device via the second network.
 15. Acommunication device as claimed in any one of the preceding claims,wherein the first network is a radio network.
 16. A communication deviceas claimed in any one of the preceding claims, wherein the secondnetwork is a radio network.
 17. A distributed radio system, comprising aplurality of communication devices as claimed in any one of thepreceding claims, each of said communication devices being linked viasaid second network.
 18. A radio network base station which is adaptedto communicate with a first communication device via a secondcommunication device using a local wireless link, wherein said first andsecond communication devices are in accordance with any one of claims1-16.
 19. A method of communicating network information on a firstnetwork within a distributed radio, comprising the steps of setting upthe distributed radio by establishing a local wireless link between aplurality of devices; nominating one of said devices as a first networkmonitoring device; and communicating network information to some or allof the remaining devices by means of the monitoring device and the localwireless link.
 20. A method for preservation of bandwidth used by aplurality of radio devices connected to a radio network, comprising thesteps of establishing a local independent wireless link between saidradio devices; nominating one of said radio devices as a monitoringdevice; switching off radio links to said radio network of some or allof the other radio devices; and communicating information received froma base station of said radio network to one or more of said other radiodevices by means of the monitoring device and the local independentwireless link.
 21. A method of allowing a radio device to monitor asignal on more than one channel or mode, when said radio device is inclose proximity to a plurality of other radio devices, comprising thesteps of establishing a local independent wireless link between saidradio devices; setting said radio devices to monitor on different modesor channels; exchanging information obtained by different devices on thelocal independent wireless link.
 22. A method of reducing processingrequirements for generating an air interface mode radio transmission, byusing a distributed radio to simultaneously monitor the current carrierfrequency and a proposed new carrier frequency.
 23. A method offacilitating W-CDMA interfrequency handover by using a distributed radioto simultaneously monitor the current carrier frequency and a proposednew carrier frequency.
 24. A communication device substantially asdescribed herein with reference to the attached drawings.
 25. A methodof distributing information amongst communication devices substantiallyas described herein with reference to the attached drawings.